1. Field of the Invention
The present invention relates to a method of forming and visualizing a latent image, an authenticity assessment method which can be applied to prevention of fraud, such as counterfeiting or falsification, and a method of recording and reproducing classified information.
2. Description of the Related Art
In order to prevent counterfeiting of valuable instrument, etc., special printing, such as hologram printing, is performed on or watermarks are embedded into part of credit cards, valuable instrument, etc. Such cards and valuable instrument cannot be easily copied by a color copying machine or the like, and thus are effective in preventing counterfeiting to a certain extent. However, holograms or watermarks themselves can be counterfeited, and the effect of preventing counterfeiting is not sufficient.
Furthermore, in another method for preventing counterfeiting, information that shows the authenticity is provided in the form of a latent image in part of credit cards, valuable instrument, etc., and by visualizing the latent image, the authenticity is verified. As such a latent image, a polarized latent image is known (refer to Japanese Unexamined Patent Application Publication No. 2007-121388).